The need for reliable broadband communication networks to deliver data services such as voice over internet protocol (VoIP), video, internet web data, email, file sharing, stereo over IP, and other such services is increasing. In response to these demands, the communication infrastructure is expanding to include many types of communication networks beyond the public switched telephone network. A power line communication system (PLCS) is an example of a communication network in the expanding communication infrastructure.
A PLCS uses portions of the power system infrastructure to create a communication network. In addition to carrying power signals, existing power lines that run to and through many homes, buildings and offices, may carry data signals. These data signals are communicated on and off the power lines at various points, such as, for example, in or near homes, offices, Internet service providers, and the like.
There are many challenges to overcome when using power lines for data communication. For example, devices that communicate over power lines, such as medium voltage power lines, need a method of coupling data signals to and from the medium voltage power line. Medium voltage power lines can operate from about 1000 V to about 100 kV, and often carry high amperage. Consequently, coupling to a medium voltage power line gives rise to safety concerns for the user installing the coupling device.
The coupling device should be designed to provide safe and reliable communication of data signals with a medium voltage power line—carrying both low and high current—in all outdoor environments such as extreme heat, cold, humidity, rain, wind, high shock, and high vibration. Also, because many power line communication devices are connected to a low voltage power (and its associated coupler), the coupler must be designed to prevent that dangerous MV voltage levels from being provided to the customer premises on the low voltage power line. In addition, a coupling device should be designed so that it does not significantly compromise the signal-to-noise ratio or data transfer rate and facilitates bi-directional communication. In addition, the coupling device (or coupler as referred to herein) should enable the transmission and reception of broadband radio frequency (RF) signals used for data transmission in MV cables.
Finally, because a coupler may used throughout a PLCS, it must be economical to manufacture and easy to install by power line personnel. Various embodiments of the coupler of the present invention may provide many of the above features and overcome the disadvantages of the prior art.